The current study examined how specific coping strategies mediate the relationship between Conscientiousness (C) and positive affect (PA) in a large, multiethnic sample. Using an internet-based daily diary approach, 366 participants (37.6% Caucasian, 30.6% Asian American, 20.7% Hispanic, 9.1% African American) completed measures that assessed daily stressors, coping strategies used to deal with those stressors, and PA over the course of five days. In addition, participants completed a measure of the Five-Factor Model of Personality. Problem-Focused coping partially mediated the relationship between C and PA. Individuals higher in C used more problem-focused coping, which, in turn, was associated with higher PA. The findings of the current study suggest C serves as a protective factor from stress through its influence on coping strategy selection. Other possible mediators in the C-PA relationship are discussed.